


Marking

by Yū (RGR1087)



Series: Kinktober 2018 [6]
Category: IDOLiSH7 (Video Game)
Genre: Alpha Yaotome Gaku, Alpha/Beta/Omega Dynamics, Alpha/Omega, Barebacking, Biting, Bottom Nanase Riku, Cock Worship, Established Relationship, Kinktober, Kinktober 2018, Knotting, M/M, Male Intersex Omegas, Mating, Omega Nanase Riku, Top Yaotome Gaku, Vaginal Fingering, Vaginal Sex
Language: English
Status: In-Progress
Published: 2018-10-06
Updated: 2018-10-06
Packaged: 2019-07-25 23:32:24
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,099
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16207967
Author URL: https://archiveofourown.org/users/RGR1087/pseuds/Y%C5%AB
Summary: Gaku couldn't wait to mark up Riku's skin with his bites, to sink his teeth into that delicious skin. The mere thought of sucking bruises onto Riku's skin had Gaku buck his hips into the wet heat of Riku's mouth. He loved seeing his marks on his Omega, the proof that Riku had chosen him and no one else.





	Marking

**Author's Note:**

> I've elected to give male Omegas a vagina and female Alphas a penis in my Omegaverse. I don't have a problem with reading the ones, where male Omegas are designed to give birth anally (I actually enjoy them a lot), but I don't really write it. I have a larger story planned, where I will explain the schematics of my Omegaverse more closely, but it's irrelevant to this story.
> 
> Please be careful when engaging in sexual activities and do your research beforehand, especially when engaging in BDSM.
> 
> Also, very important: Asthma can impact a person’s sex life. Since I’m taking part in Kinktober 2018 to get back into writing smut, I have elected to ignore Riku’s asthma for the most part. However, if you have asthma, please be careful when engaging in sexual activities and please make sure your partner is fully aware of it. And before anyone else comments that it's patronising of me to assume people with asthma need to be told by fanfic writers how to manage their health: There is a chance of young, impressionable people reading my fics. I did start reading explicit, kinky stuff around the age of twelve myself. There's also the fact I might be accused of recklessly endangering said impressionable people by not giving the warning. Riku, one of the characters involved in all the kinky stuff, has asthma in canon. Yes, some of the stuff I've written is dangerous for other people as well, but asthma heightens the risks. In addition, I have lost three of my friends because they did not tell their partners they had asthma while engaging in sexual activities of any type, not just BDSM or breath play, which is why I'm putting these notes on every explicit piece as long as a character with asthma is involved.

"Nanase-san, what is this?" Iori asked his voice stern and perhaps a bit angry. Riku dropped his arms back to his sides from their stretched position above his head. Turning around to face the younger man, he tilted his head to the side in a questioning manner. By now, all other members of IDOLiSH7 had turned their attention to the pair.  
"I'm talking about this", Iori reinforced grabbing Riku's training shirt and lifting it up without warning. Riku's resulting squeak was drowned out by the gasps and shocked exclamations of the others. There, right above Riku's left hip bone, a dark bruise was blossoming.  
In an instant, Riku slapped Iori's hand away and pulled his shirt down to cover the large bruise. His face burned with a fierce blush. On the inside, he winced. He had completely forgotten about the marks. That one wasn't the only one. The ones in easily visible places, he had covered up with make-up, but he had not thought to take extra measures for the ones hidden beneath his clothing.  
"It's nothing to worry about", Riku told them his face still blazing. He hoped they would just drop it and assume the bruise had been caused by his usual clumsiness.  
"That's not nothing, Nanase-san. Did someone hit you?" Iori insisted. The other members, who had now crowded around their centre, made their agreement known. Riku shot them an incredulous look.  
"No one hit me", Riku groaned wishing a hole would open up and swallow him.  
"Riku, you don't have to hide it. We'll protect you from the bad guy", Mitsuki reassured the redhead with a soothing voice. Riku almost wanted to bang his head against a wall.  
"I'm telling you, no one's hitting me. I just ran into a table corner one too many times", Riku insisted with a whine. It wasn't exactly the truth, but there was no way he could tell them where the bruises really came from. He wasn't ready to let them know.  
"Riku-kun, you know you can talk to us if you have problems, right? We don't think of you any less for being an Omega", Sōgo interjected. The concern blew away any mounting agitation Riku felt. He was the only Omega in their group, while Iori, Yamato and Sōgo were Alphas. The other three were Betas.  
"I know. But this really isn't anything you have to worry about", Riku sighed dragging a hand through his hair. Before anyone else could say anything, their manager entered the training room and let them know that it was time to head for their next recording.

 

The joint recording with TRIGGER and Re:vale had taken ages. Riku could not deny that for once he was glad that they were done. In addition to the long hours, the worried stares of his group members had been driving him crazy. TRIGGER and Re:vale had picked up on it as well, which had made it worse. They all knew about his secondary gender.  
"Everything all right?" Gaku whispered in his ear after his two group members had gone ahead to change. Riku sighed with relief at the welcome presence of the Alpha. His own group members were busy looking at the recordings.  
"Just exhausted. Iori saw one of the bruises by chance and they jumped to conclusions", Riku mumbled tempted to lean back into Gaku's body. Gaku, knowing about IDOLiSH7's protective behaviour when it came to their sole Omega member, didn't need Riku to elaborate. He nuzzled Riku's scent gland very briefly no matter how much he wanted to soak the other in his scent.  
"I'll see you tonight?" Gaku requested when he withdrew. Riku gave an affirmative hum, which earned him a small peck on the cheek from Gaku. They parted ways, each joining their respective group members.

 

The following weeks were a tad more stressful for Riku. He took extra care to cover up his bruises after Iori had caught sight of one by accident. That meant he had to spend extra time in the morning to make sure he had covered them all up. However, despite his efforts, his group members took quite some time until their behaviour was back to normal. The hovering and constant not so subtle probing drove him mad.  
Even after everyone's behaviour had gone back to normal, Riku was still grateful when he finally had an entire day to himself at the dorm. Everyone else would be out the entire day on jobs. Even better, Gaku had the day off as well. That was how he ended up in the dorm's training room with the Alpha, dancing and singing.  
By afternoon, the pair was drenched in sweat and ready to take a break. They plopped down on the floor, Riku making himself comfortable between Gaku's legs with his back to the older man's chest. The moment he leaned his weight back, one of Gaku's arms came around his torso forming a loose embrace. With the other, he reached for his for a water bottle, which he handed to Riku, who took a couple of eager gulps. When Riku was done, he passed the bottle to Gaku.  
While Gaku was taking his own gulps of water, Riku began squirming around a little trying to get more comfortable. Riku did not except Gaku to spew out water and double over. His chin dug into Riku's shoulder and his arm tightened around Riku. Riku blinked in surprise while Gaku groaned.  
"Riku, please don't squirm like that", Gaku mumbled with a strained voice. Riku tilted his head with a puzzled look. A few seconds ticked by until he became aware of the pressure against the small of his back and the musky scent permeating the room.  
"Are you……?" Riku hedged with a soft voice pressing himself back into Gaku. Another groan escaped the older man, this time tinged with need. Riku turned thoughtful for a moment. Then he squirmed out of Gaku's hold and turned around to face Gaku. The Alpha's scent was already beginning to affect him. Riku got on all fours, which earned him a strangled noise from his lover. He reached to open Gaku's trousers, but a hand stopped his own in their track.  
"Are you sure?" Gaku asked. The question was so simple, but Riku could tell with ease what his lover was asking of him.  
"Everyone's out for the entire day and it's been so long", Riku breathed looking straight at Gaku with an imploring gaze. The stare-down lasted for mere seconds. Gaku removed his hand placing it back on the floor to support himself and leaned back to give the other better access.  
With practised movements, Riku undid the strings of Gaku's trousers. He pulled both the trousers and boxers down just enough to be able to tug Gaku's cock out of its confines. Riku could feel a small amount of slick leaking out at the sight of his lover's magnificent cock. In his opinion, it was perfect in size and shape. His girth was above average. Beautiful.  
"You're a real cock slut, aren't you?" Gaku purred as he watched Riku drool at the sight his cock. He also didn't miss the scent of slick being produced from the Omega. It wasn't much yet, but that would change soon. A low, keening sound escaped Riku. He would never deny that he loved Gaku's cock. It was just perfect for him.  
With one hand, Riku took a gentle hold on Gaku's cock. With the other, he supported himself. He placed a feather-light kiss on the top of his lover's cock. Using his thumb, he massaged a spot right above the base with soft pressure eliciting a small moan from Gaku.  
"Only for you. It's beautiful. So strong. So powerful", Riku murmured with adoration. He lapped at Gaku's cock with kitten licks making sure to not leave out a single spot. Then he kissed along the underside of the cock until he reached the tip again. Taking the tip into his mouth, he sucked lightly tasting the first beads of precum.  
The whole time, Riku kept his eyes on Gaku, who watched him with a heated gaze. A light flush adorned Gaku's pale cheeks. When he got onto his elbows in order to use his other hand to fondle Gaku's balls, his lover's cock slid a bit further into his mouth. The sight of Gaku licking his lips sent a small shiver through Riku's body.  
Riku moved down on Gaku's cock until it hit the back of his throat before pulling off. He continued to fondle Gaku's balls while starting to pump his cock with slow strokes.  
"I love how full your cock makes me feel. Love how it stretches me", Riku cooed with reverence as he nuzzled the tip of Gaku's cock smearing some precum across his cheek. Then he took the cock into his mouth again. He bobbed his head up and down, sucking on Gaku's cock. He swirled his tongue around it from time to time. His pants were starting to get soaked with slick.

Gaku watched as his cock disappeared into his lover's mouth again and again. He smirked licking his lips and absolutely loved the shiver his action caused. He wondered what the others would think if they saw the cute little centre on his knees worshipping Gaku's cock. Lips red and swollen glistening with saliva. With such obvious adoration and reverence.  
A quiet moan escaped Gaku when Riku's tongue dipped into the slit of his cock. His breathing began to pick up and he leaned back onto his elbows to get a better view of Riku. It also made it easier to keep eye contact. The smell of Riku's slick and pheromones got stronger as time went on. A flush had spread across the redhead's skin and his eyes were glazed over with lust.  
Gaku couldn't wait to mark up Riku's skin with his bites, to sink his teeth into that delicious skin. The mere thought of sucking bruises onto Riku's skin had Gaku buck his hips into the wet heat of Riku's mouth. He loved seeing his marks on his Omega, the proof that Riku had chosen him and no one else.  
Gaku reached up with one hand to pet Riku's head before giving his hair a soft tug. Riku followed the silent command releasing Gaku's cock. Then Gaku manoeuvred his lover into a lying position placing himself between his legs.  
Another shiver ran through Riku's body when Gaku slid his hand beneath Riku's shirt. He massaged the skin for a moment before using both hands to pull Riku's shirt and jacket up exposing his torso. Leaning down, Gaku began sucking beneath Riku's ribcage. His hands moved up and down his lover's sides massaging them.  
Small moans and mewl tumbled from Riku's mouth, his cock hard and slick soaking through his trousers. The scent of Gaku's Alpha pheromones heightened his arousal. Gaku nibbled along Riku's torso until he reached a nipple. He licked across it a couple of times, then sucked on it.  
One hand trailed south and pulled Riku's trousers down. Riku lifted his hips shakily to facilitate the process allowing his lover to pull them down his knees. Gaku straightened himself up earning a whine from the redheaded Omega. He hushed him with soft reassurances as he worked to remove Riku's trousers completely. When done, he threw them to the side.  
Gaku returned his attention to Riku's nipples, while he let one hand dance around both of Riku's holes. While he lavished Riku's nipples with his tongue and teeth, he pondered with hole he should use today. It had been a while since he had fucked Riku's pussy and the Omega was on contraceptives.  
Decision made, Gaku bit down on Riku's nipple at the same time his plunged two fingers into Riku's pussy eliciting a drawn-out moan from Riku. A litany of curses escaped him as he threw his head back at the painful pleasure.  
As Gaku continued working his fingers in and out of Riku's pussy, he bit and sucked on every inch of skin he could reach leaving blossoming bruises in his wake. At times he would bite down harsh enough to draw a few drops of blood.  
Riku's pleasured screams and moans were music to Gaku's ears. He absolutely adored Riku and loved driving him crazy with pleasure, making him squirm and writhe. He was more than grateful that Riku indulged his love for marking him up. It had worried him in the beginning when he noticed the urge to mark Riku, to leave physical proof that Riku was his.  
Working a third finger into Riku's pussy and sucking on his collarbone, Gaku recalled the first time he had been unable to hold back and had bitten Riku stronger than he had ever dared. The sight of his bite mark on Riku's skin had sent him over the edge. They had talked about it afterwards and it had turned out, Riku liked having proof of being Gaku's on his skin as much Gaku did.

Straightening up, Gaku admired his handiwork. Bruises and bite marks were littering Riku's torso and tights. His hair was dishevelled, chest heaving, drool trickling down the corners of his mouth. His shirt and jacket were bunched up beneath his armpits. Gaku groaned at the erotic vision his Omega made.  
"Turn around", Gaku ordered with a rasping voice as he pulled out his fingers. Riku whined at the loss but did as he was told. As soon as Riku was on all fours, Gaku pulled Riku's shirt and jacked over Riku's head but made no move to remove them completely.  
Gaku lined himself up with Riku's pussy and began pushing in slowly. With his hands, he massaged Riku's hipbones. He bent over kissing and nipping at his lover's neck until he was fully sheathed inside the slick heat. They stayed still for a moment, Gaku nuzzling the back of Riku's neck.  
Using one hand, Gaku turned Riku's head to the side to give a deep kiss. Then he returned the hand to the redhead's hips. Then he began to move with slow thrusts. His mouth latched onto Riku's shoulder blades. As he continued his unhurried thrusts, Gaku set out to leave his marks on Riku's back as well.

Riku pressed back against each of Gaku's shoves, clenching down on the cock buried inside him. He felt every single mark Gaku left, even long after he had moved on to create a new one. His body was quivering, his mind heated and dazed. The feeling of those marks left him intoxicated.  
A jolt ran up Riku's spine when one of Gaku's hands began fondling his nipples. His arms collapsed unable to carry his weight. The new angle allowed Gaku to go even deeper drawing moans of Gaku's name from Riku's lips.  
Gaku's other hand took a hold of Riku's neglected cock. He thumbed over Riku's slit causing him to moan and clench down on Gaku's cock. The sudden tightness drew a curse from Gaku as he stilled his thrusts. Gaku's heavy breaths ghosted across Riku's skin sending electricity running across Riku's body.  
"Riku, can I?" Gaku pleaded, his voice strained and filled with lust. Riku clenched down on Gaku's cock to tease his Alpha a bit drawing a chocked moan from his Alpha's lips.  
"Yes", Riku whimpered pushing back against his lover's hips. That was all the permission Gaku needed. He drew back and snapped his hips forward. He set a fast and rough pace licking and biting at Riku's shoulders. His swelling knot began to catch on Riku's rim filling the Omega with anticipation.  
Gaku placed his hands over Riku's interlacing their fingers as he continued to pound into Riku. Their moans mixed creating their favourite private song. As Gaku felt his climax nearing, he focused his attention on Riku's scent gland, licking and nuzzling. It filled Riku with anticipation, knowing what would happen the moment his Alpha reached completion.  
Riku was so far gone that he did not pick up on the sudden additional scents or the sound of the door to the training room opening. Gaku, however, did. He buried his knot inside Riku as it swelled to its full size locking him inside Riku and bit down Riku's scent gland with a growl, strong enough to draw blood.  
A delicious scream erupted from his Omega as Gaku emptied himself into Riku. The Omega's body jerked with his own orgasm as his cum dripped down onto the floor, pussy clenching down to milk Gaku's cock for everything it could give.  
Gaku snarled dangerously at the intruders. Despite his teeth still buried in Riku's neck, the snarl still sent the intruders scrambling to get out of the room, the door slamming shut behind them. As the pair came down from their orgasm, Gaku carefully manoeuvred them to lie on their sides. He dislodged his teeth and licked at the wound until the bleeding stopped.  
Riku lay boneless against Gaku's chest, soft purrs escaping his chest. Gaku continued nuzzling his neck and patted his head murmuring sweet words to his Omega. At some point, Gaku moved onto his back pulling Riku to lie on him, back to chest. A moan escaped Riku as the action pushed the knot deeper.  
They stayed like that basking in each other's presence until Gaku's knot deflated. Gently, Gaku sat up and removed the remaining garments Riku was wearing and placed the shirt beneath them. When he lifted Riku off his cock, a mixture of cum and slick gushed out of his pussy soaking the shirt. Riku whined but was appeased with a kiss from his Alpha.  
"The others walked in on us earlier", Gaku murmured once he had gotten Riku settled back into his lap. Riku let out a mortified groan. He was not looking forward to the lectures they would get. Iori and Ten were the ones he was most worried about. Less about their acceptance of his relationship with Gaku and more about what they might do to his Alpha.  
"Shhh. We'll get through this", Gaku soothed his Omega as soon as he picked up his distress. They should probably first get cleaned up and dressed before facing everyone else. Riku whole-heartedly agreed with that suggestion. As much as he loved post-mating cuddling, the drying slick and cum were getting uncomfortable. Gaku made quick work of redressing both of them, tugging Riku's shirt into his training bag before carrying his Omega to the bathroom. Thankfully, they didn't encounter anyone on their way.

**Author's Note:**

> Find me on Tumblr ([Yū's Creativity Blog](http://yuscreativityblog.tumblr.com/)), Twitter ([@RGR1087](https://https://twitter.com/RGR1087)) or IDOLiSH7 Amino ([Yū's IDOLiSH7 Amino](http://aminoapps.com/p/tiwc1s))


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